Vulcanization of rubber



Patented Mar; 29, I932 UNETED STATES PATE HUGH MILLS BUNBURY AND WILLIAM JOHNSON SMITH NAUN'ION,

or (MANCHESTER,

AND WILIERELD ARCHIBALD SEX'ION, or HUDnERsFI'ELn, ENGLAND, ASSIGNORS 'ro l IMPERIAL CHEMICAL INDUSTRIES LIMITED, A CORPORATION OF BRITAIN VULGANIZA'IION or Rosana No Drawing. Application filed May 1, 1931, Serial No. 534,442, and in Great Britain April 30, 1930.

It is well known that vulcanization accelerators are obtained by combining together amines and mercaptoarylenethiazoles, e. g. 2- inercapto-benzthiazole. Such accelerators, however, do not possess what is a desirable property, namely, that of delayed action. By this we mean that the accelerating function is only exerted above a certain temperature, so that there is no risk of premature vulcanization taking place, e. g. during milling operations.

It is the object of the present invention to provide vulcanization accelerators having this desirable property.

We have found, and our invention is based in the discovery, that vulcanization acceleraors having this desirable property of delayed iction are obtained by combining together a iitro derivative of an aromatic amine and a nercaptoarylene thiazole, e. g. Q-mercapto- )enzthiazole, and commingling the product vith a basic organic accelerator such as a liphenylguanidine.

l Ve find that when the compounds of a litro derivative of an aromatic amine and Inercaptoarylene thiazole are used alone hey are but feeble accelerators, even at such emperatures as 140 0., whereas, while such oixtures as are made in accordance with our nvention are devoidor almost devoid of acelerating properties at low temperatures, ven at, e. g. 110 0., they are rapid accelera- )l'S at higher temperatures, e. g. 140 G.

Our invention is illustrated, but not lim- Jed by the following example, in which the arts are by weight.

Example 167 parts of mercaptobenzthiazole are ised with 138 parts (i. e. an equimolecular voportion) of p-nitro-aniline, and the resultlg resinous product is pulverized. Alternavely the product may be obtained by heatlg the substances together in alcoholic solution. It is believed to be a salt-like compound represented by the formula 0.25 parts of the product so obtained are in corporated together with 0.25 parts of dipenhylguanidine into a rubber mix composed of pale crepe rubber 100 parts, zinc oxide parts, barytes 75 parts and sulphur 2.5 parts. Vulcanization is carried out at a temperature of 141 C. for a period of minutes. The rubber then has a tensile strength at break .of 143 kilog. per sq. cm. When the vulcanization is effectedvat 110 C. for minutes, the cure is incomplete.

The comparative inefi'cctiveness of the product when used alone is illustrated by the following. 0.5 parts of the product were incorporated into a similar rubber mix. Vulerator and a compound obtainable by fusing together equim'olecular proportions of' a. mono-nitro-aniline and 2-mercaptobenzthiazole. V I

2. A process for the manufacture of vulcanized rubber which comprises heating a rubber mix containing as vulcanization accelerator a mixture of a basic organic accelerator and a compound obtainable by fusing together equimolecular proportions of pnitroaniline and Q-mercaptobenzthiazole.

3. A vulcanization accelerator which comprises a basic organic accelerator and a compound obtainable by fusing together a mononitroaniline and Q-mercaptobenzthiazole. V 4. A vulcanization accelerator which comprises a basic organic accelerator anda com- 7 pound having the formula: N01

O.SH.NH: O S

In testimony whereof we aifix'iour sign atures... v

HUGHMILL'S BUNBURY. WILLIAM JOHNSON SMITH NAUNTON. WILFRED ARCHIBALD SEXTON. 

